High pressure water systems are found in fire engines and are used to pump large volumes of water under pressure to supply fire hoses for fighting fires. Capped connection fittings for these high pressure water systems are positioned on fire engine control panels for connecting fire hoses and other water lines. Typically, these connection fittings are closed off with a cap which engages the fitting by complementary threads. The pipes, fittings, valves, and end caps in these systems are manufactured of high strength materials such as stainless steel, so that they will maintain their integrity in the high pressure environment.
A particular problem in these high pressure water systems, and safety hazard to firefighters, occurs when loosening and removing an end cap from a system outlet which may be pressurized. It is well known in the firefighting arts that such a cap loosened from a pressurized outlet may become a dangerous projectile when dislodged and propelled outwardly by the pressure in the system. For that reason, outlet caps are typically attached to the outlet fitting by a short chain which tends to prevent the cap from flying away from the fitting if loosened when the system is pressurized.